From the situations about the incomes and life quality of the urban and rural residents, the thesis briefly introduces the status quo of the urban-rural income gap and explores the impact of the income gap on social economy: firstly, it hampers economic development; secondly, it is detrimental to the social development. Then the thesis analyzes the role of a sound social security in narrowing urban-rural income gap: at first, it broadens the institutional environment of improving the agricultural efficiency; secondly, it eliminates the uncertainties influencing the farmers’ income; thirdly, it improves the farmers’ capacity to increase income; at last, it enhances the farmers’ consciousness of wealth. Next the thesis inquires into the problems existing in the system of rural social security: the first problem is more obviously fragmented system; the second is inadequate security projects and narrower coverage; the third is an obvious lack of equality in urban and rural security; the fourth is even less sound management system; the last is the lagging of legislation. Afterwards the thesis proposes the countermeasures and suggestions to improve the system of rural social security and narrow urban-rural income gap: firstly, to integrate the social security system in rural areas; secondly, to perfect security projects and enhance the security system; thirdly, to integrate the administrative management of social security; at last, to enforce the legal system.